Polyurethane from ethylene-hydroxyalkyl acrylate copolymers



a I l This invention relates to new resinous materials and their preparation. More particularly, the invention relates to new polyurethane resins prepared from a special type of polyol and to the use of the polyurethanes, particularly in the preparation of foamed or cellular materials.

It is an object of the invention to provide new resinous materials. H is a further object to provide new and improved polyurethane resins which are particularly useful and valuable in industry. It is a further object to provide new polyurethane foams having improved resistance to water. It is a further object to provide improved polyurethane foams from certain resinous polyols. These and other objects of the invention will be apparent from the following detailed description thereof.

It has now been discovered that these and other objects may be accomplished by the compositions of the present invention comprising the reaction product of an organic polyisocyanate and a resinous polyol consisting of a polymer of ethylene selected from the group consisting of copolymers of ethylene and ,B-hydroxyalkyl acrylates having the general formula wherein R is a hydrogen atom or a methyl group and G is an alkylene group containing 2 to 8 carbon atoms, and terpolymers of ethylene, said fl-hydroxyalkyl acrylate and alkyl acrylates having the general formula wherein R is a hydrogen or a methyl group and R is an alkyl group having 1 to 8 carbon atoms, and mixtures thereof.

Representative examples of fi-hydroxyalkyl acrylates suitable for the preparation of the ethylene polyols of the present invention include hydroxyethyl acrylate and methacrylate, hydroxypropyl acrylate and methacrylate, hydroxybutyl acrylate and methacrylate and hydroxyhexyl acrylate and methacrylate and hydroxyoctyl acrylate and methacrylate.

Representative examples of suitable alkyl acrylates which are useful for the preparation of terpolymer polyols of the present invention include methyl acrylate and methacrylate, ethyl acrylate and methacrylate, propyl acrylate and methacrylate, butyl acrylate and methacrylate, isobutyl acrylate and methacrylate, 2-ethyl hexyl acrylate and methacrylate.

It has been found that the polyurethane resins prepared from the above described ethylene polyols have many unexpected properties which enable them to be utilized for a wider field of application than the conventional polyurethane products. It has been found, for example, that the new polyurethane resins have unexpected resistance to water. The new polyurethanes prepared from the hydroxy-containing derivatives of the resinous copolymers also having surprisingly good flexibility and resistance to impact at low temperature. The new polyurethanes have been found to be particularly useful in preparing foams for structural applications.

itcd States Patent 3,2844% Patented Nov. 8, 1956 The ethylene/,B-hydroxyalkyl acrylate copolymers, and ethylene/,B-hydroxyalkyl acrylate/alkyl acrylate terpolymer used to prepare the novel polyurethane compositions of the present invention are prepared by polymerization of mixtures of ethylene and a fl-hydroxyalkyl acrylate, and the alkyl acrylate if the terpolymer is desired, either in tubular or stirred autoclave reactors at pressures from about 15,000 to about 35,000 pounds per square inch or higher, at temperatures from about 100 C. to about 300 C., preferably from about 150 C. to about 260 C. using, at catalytically effective concentration, polymerization catalysts such as peroxygen-type catalysts or other freeradical producing materials such as the azo catalysts or others well known in the art.

The preparation of these copolymers are more fully disclosed in co-pending application Serial No. 321,684 of George E. Waples, lr., filed November 6, 1963.

The ethylene/fi-hydroxyalkyl acrylate copolymers advantageously employed to prepare the polyurethane compositions of the present invention contain about 65 percent to about 96 percent by weight ethylene and from about 4 percent to about 35 percent by weight of the fi-hydroxyalkyl acrylate. The ethylene/fi-hydroxyalkyl acrylate/alkyl acrylate terpolymers advantageously employed to prepare the polyurethane compositions of the present invention contain about 61 to about percent ethylene, about 4 to about 315 percent p-hydroxyalkyl acrylate and about 1 to about 35 percent of an alkyl acrylate. The average molecular weights of these copolymers range from about 800 to 6000 and in this molecular weight range the physical state of the copolymers at room temperature ranges from oily fluids to very hard Waxes. Also in this molecular weight range the copolymers have a hydroxyl content of about 0.6 to about 6.0 percent and an average hydroxyl functionality ranging from about 1.75 to about 21.

In order to prepare useful foams with polyisocyanates, it is desirable that copolymers having a molecular Weight of from about 500 to about 4000 and preferably from about 1500 to about 2500 and an average hydroxyl functionality of at least 2.0 and more preferably about 2.2 to about 14 be used. At molecular weights above 4000 the copolymer is too viscous to be used as a foaming material for most applications without the use of special apparatus and at a hydroxyl functionality of less than 2.0, the foams produced have little strength.

Representative examples of organic polyisocyanates that can be used to make the polyurethane resins of the present invention include 2,4tolylene diisocyanate, 2,6- tolylene diisocyanate, the phenylene diisocyanates, the naphthalene diisocyanates, 1,2,4-benzene triisocyanate, hexamethylene diisocyanate, trimethylene diisocyanate, methylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,3-cyclopentylene diisocyanate, and mixtures thereof. Arylene diisocyanates, that is, those in which each of the two isocyanate groups is attached directly to an aromatic ring, are preferred.

The reaction between the organic polyisocyanate and the ethylene/fi-hydroxyalkyl acrylate copolymer or the ethylene/,B-hydroxyalkyl acrylate/alkyl acrylate terpolymer may be carried out in a variety of Ways. The reaction may be accomplished by merely mixing the reactants together at room temperature. Preferably the ethylene copolymer or terpolymer is preheated to a temperature in the range of 80 to C. and the polyisocyanate heated to a temperature of about 30 to 50 C. is added to the hot ethylene polymer.

The proportions in which the reactants may be combined can be varied widely, depending chiefly on the intended application. For the preparation of foams it is generally preferred to combine the organic polyisocyanate 3 and the ethylene polyol in chemical equivalent ratios varying from about 0.95: 1.0 to about 1.05: 1.0.

Polyurethane resins are made in cellular form from the organic polyisocyanate and ethylene fl-hydroxyalkyl acrylate copolymer or ethylene/,B-hydroxyalkyl acryl-ate/ alkyl acrylates terpolymer by adding water or a carboxyl group-containing compound to the reaction mixture whereby carbon dioxide is liberated which causes the liquid reaction mixture to expand and foam. Alternatively, a polyurethane foam may be made by admixing a blowing or foaming agent with one of the reactants, namely, the polyisocyanate, before they are mixed. The blowing agent and the reactants can all be brought together simultaneously or the blowing agent can be mixed with the reactants shortly after they are brought together. Representative examples of suitable blowing agents which can be used for this purpose are trichloromonofluoromethane, hexane, methylchloroform, symmetrical tetrachlorodifiuoroethane, trichlorotrifiuoroethane, dichloromethane, benzene, and in general any organic solvent which will readily boil at the desired foaming temperatures yet not react with the organic polyisocyanate or ethylene polyol.

A catalyst for the reaction between the polyisocyanate and the polyol copolymer or terpolymer can be used for making the foamed urethane polymers of the present invention Representative examples of suitable catalysts are dibutyltin dilaurate, cobalt naphthenate, stannous octoate, and tertiary amines such as triethylamine, N-methyl morpholine and N,N'-dimethyl ethanolamine.

If desired, a cell-size control agent can be added to the reaction mixture. Representative of suitable cell-size control agents are polyorgano siloxanes such as liquid polyalkyl siloxanes including polydimethyl and polydiethyl siloxanes, polydipropyl siloxanes, and liquid polyaryl siloxanes, including polydiphenyl siloxane, or mixed polyarylalkyl siloxanes such as polymethylphenyl siloxanes or liquid mixtures of one or more of such siloxanes.

The formulations of this invention can be made by batch methods employing either hand mixing or simple stirring equipment. Several types of mechanical equipment are available which can automatically meter the constituents to a mixer and dispense foams in predetermined quantities. This equipment can be run either continuously or intermittently.

The polyurethane compositions of this invention can be made into useful articles by conventional molding, casting, coating, and laminating techniques. Foams of these compositions can be cast onto a conveyor belt to produce sheets or slabs of polyurethane foams which may then be cut up into convenient sizes. The foams made from the compositions of this invention can be cast in molds to make desired shapes or the foams can be cast in place to fill voids in a final article as in the strengthening of double-walled members.

The following examples are illustrative of the present invention, but the invention is not limited thereto.

4 EXAMPLE 1 A polyurethane foam was prepared using the following components: 5 Component I Mixture containing: Ethylene/[i-hydroxypropyl acrylate copolymer grams 100 Comprised of 79.2 percent by weight ethylene l0 and 20.8 percent by weight 3-hydroxypropyl acrylate having the following physical properties:

Hydroxyl content, percent 2.66 Hydroxyl functionality 2.35 Molecular weight 1500 Physical state Grease Silicon L-520, polymeric tetraethyl orthosilicate cell size control agent manufactured by Union Carbide (L-520) cc 2 Triethylene diamine (TEDA) cc 0.25 Stannous Octoate cc 0.25 Water grams 4 Component II Mixture of: Polymethylene polyphenylisocyanate (PAPI), a

polyisocyanate having the general formula N00 IIICO NCO CH2 CH:

wherein n is an average of approximately one, the product having an isocyanate equivalent (dibutylamine) of about 133.5 and a minimum NCO content by weight of 31 percent grams 85 Ethylene dichloride (EDC) do 20 EXAMPLE 2 Polyurethane foams were prepared following the procedure of Example 1 using the ethylene polyols listed in Table I below. The concentration of the reactants and the properties of the foams prepared therefrom are listed in Table II below.

TABLE I.ETHYLENElfl-HYDROXYALKYL AC RYLATE COPOLYMER Composition of Copolymer Hydroxyl Hydroxyl Molecular Physical Sample No. fi-hydroxyalkyl content functionality weight state Ethylene acrylate (percent) (percent) Alkyl type Percent 79.4 Ethy1 20.6 3.0 1.54 881 Light Grease. 78.0 do. 22.0 3.2 10.6 5,630 ToughWax. 78.6 Propyl 21.4 2.74 2.2 1,380 Grease.

TABLE II.POLYURETHANE FOAMS PREPARED FROM AIETkgIRJgJlANIC POLYISOCYANATE AND ETHYLENE POLYMERS OF Foam Organic Polyiso- Amount Copoiyrner Amount L-520 Stannous TEDA H1O Density N0. cyanate Reacted N0. Reacted (cc.) Octoate (cc.) (grams) (lbs/it?) Appearance (grams) (grams) v (00.)

1 Methylene bis-(4- 80 A 80 1 0.25 3.5 2.16 Brown Color,

phenyl isocyanato). Semirigid. 2 Tolyleue (liisocyanate 72 B 50 l 0.20 3 1.3 White (,olor, Rigid.

(80% 2, 4; 20% 2, e). v v 3 PAPI 86 C 00 2 0.25 0.25 l 4 2.65 Brown, Semi-rigid.

1 Plus grams EDC.

EXAMPLE 3 EXAMPLE 5 A polyurethane foam was prepared following the procedure of Example 1 using the following reactants.

Componentl I Ethylene/B-hydroxyethyl acrylate copolymer grams 80 Comprised of 79.4 percent by weight ethylene and 20.6 percent by weight fl-hydroxyethyl acrylate having the following physical properties:

Hydroxyl content, percent 3.0 Hydroxyl functionality 1.54 Molecular weight 881 Physical state Silicon L-520 Light grease cc 1 Stannous octoate cc 0.25

Water grams 3.5

Component ll I Methylene bis(4-phenyl isocyanate) grams 80 The foam prepared in this manner was brown, semirigid, not friable and had a density of 2.16 lbs./ft.

EXAMPLE 4 A polyurethane foam was prepared following the procedure of Example 1 using the following reactants:

Component 1 Ethylene/,B-hydroxyethyl acrylate/ ethyl acrylate =co- Component II Tolylene diisocyanate (80% 2,4; 2,6) grams 2s The foam prepared in this manner was :white, firm flexible, non-friable and had a density of 4.6 lbs./ft.

The procedure of Example 4 was repeated with the exception that Component I was heated to 130 C. prior to mixing of the two components.

The foam prepared in this manner was white, flexible and had a density of 2.8 lbs./ft.-.

EXAMPLE 6 A polyurethane foam was prepared following the procedure of Example 1 using the following reactants.

Component I Ethylene/fl-hydroxyethyl acrylate copolymer comprised of 78.0 percent by weight ethylene and 22.0 percent by weight ,B-hydroxyethyl acrylate blended in the mixture to reduce viscosity.

Component II Tolylene diisocyanate (80% 2,4; 20% 2,6) cc The foam prepared in this manner was brown, semirigid, not friable and had a density of 1.3 lbs./ft.

EXAMPLE 7 Blends of an ethylene/fi-hydroxypropyl acrylate copolymer designated as copolyme-r D comprised of 78.6 percent of weight ethylene and 21.4 percent by weight fl-hydroxypropyl acrylate having the following physical properties:

Hydroxyl content, percent 2.73 Hydroxyl functionality 1.75 Molecular weight 1090 Physical state Light grease were made with the ethylene terpoylmers E and F listed in Table III below.

TABLE III.-ETH YLENE/B-HYD ROXYP ROP YL/ETHYL AC RYLATE COP OLYME RS v Ethylene B-hydroxy- Ethyl acrylate Hydroxyl Sample N 0. (Percent propyl (Percent content Hydroxyl Molecular Physical approximate acrylate approximate (Percent) functionality weight state values) values) 9. 7 10 1. 24 4. 4 6, 000 Hard Plastic. 81 8. 6 9 1.10 2.3 3, 550 Wax. 78 11.5 12 1. 47 2.0 2, 300 Grease.

rod.

Polyurethane foams were prepared following the procedure of Example 1 by reacting 100 parts of the polymer blends with 37 parts tolylene diisocyanate (80% 2,4; 20% 2,6) using the following amounts of water, blowing agent, catalyst and cell size regulator.

Material: Parts Water 3.5-4.0 Ethylene dichloride Stannous octoate 0.2

L-52O 2.5 Silox'ane oxyalkylene block copolymer cell size regulator of the type described in US. 2,917,480 1.0

The composition of the blends, their properties and the physical properties of the polyurethane foams prepared therefrom are summarized in Table IV below.

wherein R is selected from the group consisting of hydrogen and methyl and G is an alkylene group containing 2 to 8 carbon atoms, and

TABLE IV Composition of Polymer Properties of Polymer Properties of Foam 1 Blend Blend Foam No. Amount Tcrpolymer, Amount Hydroxyl M.W Density Tensile C .L.D

Parts Copolymer D functionality (lbs/ft!) Strength at (p (p.s.i.)

1 Procedures described in ASTM D-1564-59'1. 2 Compression Load Deflection.

What is claimed is:

1. A polyurethane composition comprising the product obtained by mixing and reacting an organic polyisocyanate with a resinous polyol selected from the group consisting of (a) a copolymer containing from about 65 to about 96 percent by weight ethylene and from about 4 to about percent by weight of a fi-hydroxyalkyl acrylate having the general formula wherein R is selected from the group consisting of hydrogen and methyl and G is an alkylene group containing from 2 to 8 carbon atoms, and

(b) a terploymer containing from about 61 to about 95 percent by weight ethylene, from about 4 to about 35 percent by weight of said fl-hydroxyalkyl acrylate and from about 1 to about 35 percent by weight of an alkyl acrylate having the formula wherein R is selected from the group consisting of hydrogen and methyl and R is an alkyl group having from 1 to 8 carbon atoms, and mixtures of (a) and (b).

2. The polyurethane composition of claim 1 wherein the organic polyisocyanate is tolylene diisocyanate.

3. The polyurethane composition of claim 1 wherein the organic polyisocyanate is methylene bis(4-pheny1 isocyanate).

4. The polyurethanecomposition of claim 1 wherein the fi-hydroxyalkyl acrylate is fi-hydroxyethyl acrylate.

5. The polyurethane composition of claim 1 wherein the B-hydroxyalkyl acrylate is B-hydroxypropyl acrylate.

6. The polyurethane composition of claim 1 wherein the alkyl acrylate is ethyl acrylate.

(b) a terpolymer containing about 61 to about percent by weight ethylene, about 4 to about 35 percent by weight of said fi-hydroxyalkyl acrylate and about 1 to about 35 percent by weight of an alkyl acrylate having the formula wherein R is selected from the group consisting of a hydrogen and methyl and R is an alkyl group having 1 to 8 carbon atoms, and mixtures of (a) and (b).

8. The polyurethane composition of claim 7 wherein the organic polyisocyanate is tolylene diisocyanate.

9. The polyurethane composition of claim 7 wherein the organic polyisocyanate is methylene bis(4-phenyl isocyanate).

10. The polyurethane composition of claim 7 wherein the fl-hydroxyalkyl acrylate is fi-hydroxyethyl acrylate.

11. The polyurethane composition of claim 7 wherein the fl-hydroxyalkyl acrylate is ,B-hydroxypropyl acrylate.

12. The polyurethane composition of claim 7 wherein the alkyl acrylate is ethyl acrylate.

References Cited by the Examiner UNITED STATES PATENTS 3,028,367 4/ 1962 OBrien 260-77.5

FOREIGN PATENTS 233,884 5/1961 Australia. 831,056 4/1957 Great Britain.

MURRAY TILLMAN, Primary Examiner.

SAMUEL H. BLECH, Examiner.

J. WHITE, Assistant Examiner. 

1. A POLYURETHANE COMPOSITION THE PRODUCT OBTAINED BY MIXING AND REACTING AN ORGANIC POLYISOCYANATE WITH A RESINOUS POLYOL SELECTED FROM THE GROUP CONSISTING OF (A) A COPOLYMER CONTAINING FROM ABOUT 65 TO ABOUT 96 PERCENT BY WEIGHT ETHYLENE AND FROM ABOUT 4 TO ABOUT 35 PERCENT BY WEIGHT OF A B-HYDROXYALKYL ACRYLATE HAVING THE GENERAL FORMULA CH2=C(-R)-COO-G-OH WHEREIN R IS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN AND METHYL AND G IS AN ALKYLENE GROUP CONTAINING FROM 2 TO 8 CARBON ATOMS, AND (B) A TERPOLYMER CONTAINING FROM ABOUT 61 TO ABOUT 95 PERCENT BY WEIGHT ETHYLENE, FROM ABOUT 4 TO ABOUT 35 PERCENT BY WEIGHT OF SAID B-HYDROXYALKYL ACRYLATE AND FROM ABOUT 1 TO ABOUT 35 PERCENT BY WEIGHT OF AN ALKYL ACRYLATE HAVING THE FORMULA CH2=C(-R1)-COO-R2 WHEREIN R1 IS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN AND METHYL AND R2 IS AN ALKYL GROUP HAVING FROM 1 TO 8 CARBON ATOMS, AND MIXTURES OF (A) AND (B). 